Comparison and validation of escherichia coli quantitative methods in cooked food (POULTRY)

Abstract

Until recently there has been little formal guidance on procedures for enumerating of E. coli in cooked food in Malaysia. This causes some difficulties in monitoring and enforcement of food safety and quality. However, various international methods were ready to be used for the microbiological parameters. First thing, the methods need to be validated with local food samples before they could be considered as national validation. Hence, this study was conducted in order to validate and compare eleven standard methods by using ISO 16140 procedure. The methods were pour, spread and drop plating, Petrifilm???, three types of direct plating and four types of MPN methods. Five types of ready-to-eat foods (poultry) were spiked with three E. coli strains which were ATCC 25922,IMR 1/3 10lB and IMR E243. The contaminated foods finally were exposed to heat at 55??C for 4 to 6 min to stress the spiked E. coli before the eleven standard methods were carried out. The correlation and relative accuracy of the data were analyzed by using the Ordinary Least-Squares (OLS) Regression. All methods gave similarities for the recovery of stressed E. coli (p<0.05). Practical approaches were also considered in order to identifY the three best methods/or the recovery of stressed E. coli infood. The observation found that pour plating, drop plating and Petrifilm' were more practical than the other methods.